Isocrania is an extinct genus of brachiopods found during the Upper Cretaceous. Early representatives were attached to the underground, but later species are presumed to be free living at an increasingly earlier age. This was probably an adaptation to the increasing very thick and fine sedimentation during the latest Cretaceous.
Isocrania is round to ovate, up to 1 cm in diameter, and has 15-65 strong ribs, that start at ±½mm from the origin of growth (or umbo). These ribs may extend beyond the edge of the valves. The umbo is not precisely in the centre of the valve. The attachment area is smaller than usual, and virtually absent in adults of later species. The dorsal valve is conical, the ventral valve flat to conical, flatter for adolescents and earlier species. The inner edge of the valves is flattened and grainy.[2]
Species and distributionedit
I. campaniensis is known from the Upper Cretaceous of Belgium (Upper Campanian, Craibel Quarry, Obourg, Craie d'Obourg and Craie de Trivieres Formations, 50.4° N, 3.9° E).[3]
I. costata has been found in the Upper Cretaceous of France (Lower Campanian, d'Avezac Formation, Tercis, 43.7° N, 1.1° W; and Upper Campanian, Tercis, Les Vignes Formation),[4] Denmark (Maastrichtian, Nye Klov 3-7, 55.5° N, 12.5° E) and the Lower Paleogene of Denmark (Lower Danian, Nye Klov 8, 9 and 20-28, 55.5° N, 12.5° E).[5] This species occurs in sediments from quiet, deep, off-shore waters, which is consistent with the fact that the preservation state is excellent and many specimens have boring holes testifying that they were predated by molluscs.[6]
^Simon, Eric (2007). (PDF). Bulletin de l'Institut Royal des Sciences Naturelles de Belgique (77): 141–157. Archived from the original (PDF) on 2014-09-24. Retrieved 2014-09-20.
^Lee, D.E.; Burton, C.H.C. (1986). "Neocrania n.gen., and a revision of Cretaceous-Recent brachiopod genera in the family Craniidae". Bulletin of the British Museum (Natural History), Geology Series. 40: 141–160. ISSN 0968-0462.
^Simon, E. (2000). "Upper Campanian brachiopods from the Mons Basin (Hainaut, Belgium): the brachiopod assemblage from the Belemnitella mucronata Zone". Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre. 70: 129–160. cited in Marko Manojlovic. "Isocrania campaniensis". Fossilworks. Retrieved 17 December 2021.
^Odin, G.S. (2001). "The Campanian-Maastrichtian stage boundary". Development in Palaeontology and Stratigraphy. 19: 1–881. cited in Loic Villier. "Isocrania costata-Cretaceous of France". Fossilworks. Retrieved 17 December 2021.
^Surlyk, F.; Johansen, M.B. (1984). "End-Cretaceous brachiopod extinctions in the chalk of Denmark". Science. 223 (4641): 1174–1177. doi:10.1126/science.223.4641.1174. PMID 17742931. cited in Karen Layou. "Isocrania costata". Fossilsworks. Retrieved 17 December 2021. and Karen Layou. "Isocrania costata". Fossilsworks. Retrieved 17 December 2021.
^Surlyk, Finn (1984). "Autecology and taxonomy of two Upper Cretaceous Craniacean brachiopods". Bulletin of the Geological Society of Denmark. 22: 219–243.
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isocrania, extinct, genus, brachiopods, found, during, upper, cretaceous, early, representatives, were, attached, underground, later, species, presumed, free, living, increasingly, earlier, this, probably, adaptation, increasing, very, thick, fine, sedimentati. Isocrania is an extinct genus of brachiopods found during the Upper Cretaceous Early representatives were attached to the underground but later species are presumed to be free living at an increasingly earlier age This was probably an adaptation to the increasing very thick and fine sedimentation during the latest Cretaceous Isocrania egnabergensis lateral view internalIsocraniaTemporal range Turonian Danian PreꞒ Ꞓ O S D C P T J K Pg NIsocrania egnabergensis 7 mm OScientific classificationDomain EukaryotaKingdom AnimaliaPhylum BrachiopodaClass CraniataOrder CraniidaFamily CraniidaeGenus IsocraniaJackel 1902SpeciesI egnabergensis Retzius 1781 type species 1 Crania engabergensis regularly misspelled as ignabergensisI barbata Von Hagenow 1842 Crania barbataI borealis Ernst 1984I campaniensis Ernst 1984I costata J Sowerby 1823 Crania costataI paucicostata Bosquet 1859 Crania paucicostataI phosphatica Simon 1998I praecostata Ernst 1984I restricta Ernst 1984I sendeni Simon 2007 Contents 1 Description 2 Species and distribution 3 See also 4 ReferencesDescription editIsocrania is round to ovate up to 1 cm in diameter and has 15 65 strong ribs that start at mm from the origin of growth or umbo These ribs may extend beyond the edge of the valves The umbo is not precisely in the centre of the valve The attachment area is smaller than usual and virtually absent in adults of later species The dorsal valve is conical the ventral valve flat to conical flatter for adolescents and earlier species The inner edge of the valves is flattened and grainy 2 Species and distribution editI campaniensis is known from the Upper Cretaceous of Belgium Upper Campanian Craibel Quarry Obourg Craie d Obourg and Craie de Trivieres Formations 50 4 N 3 9 E 3 I costata has been found in the Upper Cretaceous of France Lower Campanian d Avezac Formation Tercis 43 7 N 1 1 W and Upper Campanian Tercis Les Vignes Formation 4 Denmark Maastrichtian Nye Klov 3 7 55 5 N 12 5 E and the Lower Paleogene of Denmark Lower Danian Nye Klov 8 9 and 20 28 55 5 N 12 5 E 5 This species occurs in sediments from quiet deep off shore waters which is consistent with the fact that the preservation state is excellent and many specimens have boring holes testifying that they were predated by molluscs 6 See also editList of brachiopod genera Taxonomy of commonly fossilised invertebratesReferences edit Simon Eric 2007 A new Late Maastrichtian species of Isocrania Brachiopoda Craniidae from The Netherlands and Belgium PDF Bulletin de l Institut Royal des Sciences Naturelles de Belgique 77 141 157 Archived from the original PDF on 2014 09 24 Retrieved 2014 09 20 Lee D E Burton C H C 1986 Neocrania n gen and a revision of Cretaceous Recent brachiopod genera in the family Craniidae Bulletin of the British Museum Natural History Geology Series 40 141 160 ISSN 0968 0462 Simon E 2000 Upper Campanian brachiopods from the Mons Basin Hainaut Belgium the brachiopod assemblage from the Belemnitella mucronata Zone Bulletin de l Institut Royal des Sciences Naturelles de Belgique Sciences de la Terre 70 129 160 cited in Marko Manojlovic Isocrania campaniensis Fossilworks Retrieved 17 December 2021 Odin G S 2001 The Campanian Maastrichtian stage boundary Development in Palaeontology and Stratigraphy 19 1 881 cited in Loic Villier Isocrania costata Cretaceous of France Fossilworks Retrieved 17 December 2021 Surlyk F Johansen M B 1984 End Cretaceous brachiopod extinctions in the chalk of Denmark Science 223 4641 1174 1177 doi 10 1126 science 223 4641 1174 PMID 17742931 cited in Karen Layou Isocrania costata Fossilsworks Retrieved 17 December 2021 and Karen Layou Isocrania costata Fossilsworks Retrieved 17 December 2021 Surlyk Finn 1984 Autecology and taxonomy of two Upper Cretaceous Craniacean brachiopods Bulletin of the Geological Society of Denmark 22 219 243 nbsp This brachiopod related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Isocrania amp oldid 1099445802, wikipedia, wiki, book, books, library,
